Detect start of download start / file transfer from client side only

Question

I noticed that there is a question before asking how to \"Detect when browser receives file download\".

This requires the server to send a cookie in order to complete th

Answer 1

Edit: You can also ise an ajax call to get a base64 string of the zip and then clientside convert it to a blob in html5. But that requires to base64 encode the file server side and it increases the file size by around 33%.

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I would make an ajax call that checks is the file is already generated after starting the download with a timer:

$.ajax({
    type: 'HEAD',
    url: 'generatedfileurl',
    success: function() {
        alert('File found.');
    },
    error: function() {
        alert('File not found.');
    }
});

Then when the file is found I'd wait a few seconds and then start download nr2 since I assume that file nr1 is already downloading since it has already been generated.

It's far from ideal, I'd definitely recommend using cookies or something else serverside.